Annual reproductive cycle of black rockfish Sebastes schlegeli
in captivity
H.
Mori, M. Nakagawa, K. Soyano, Y. Koya-2003
Fisheries
Science,
69(5): 910
Abstract:
The
gonadal development and serum profiles of vitellogenin and sex steroids in
rearing Sebastes schlegeli were monitored for one full year. Female
fish began vitellogenesis from November and completed it in March. Gestation
occurred from April, and parturition occurred in June. A thin chorion and
scanty cortical alveoli are oogenetic peculiarities of this fish. Male fish
began spermatogenesis from June, and matured in November and December. It
appears that copulation occurs in November and December, and that the sperm
are stored freely in the ovary during the early vitellogenic period and
under the ovigerous lamellae epithelium during the late vitellogenic period.
Serum vitellogenin levels in female fish had a good correlation with oocyte
growth. Serum estradiol-17β (E2) levels in female fish were elevated from November to February,
suggesting that E2 controls vitellogenesis. Serum 17,20
β-dihydroxy-4-pregnen-3-one
(DHP) in female fish increased in the late vitellogenic period, suggesting
that DHP was a maturation-inducing steroid. High levels of serum DHP during
gestation suggest that it may be one of the endocrine factors for
maintaining gestation. Serum 11-ketotestosterone (11-KT) levels in male fish
were elevated from June to October, suggesting that 11-KT controls
spermatogenesis. Serum DHP in male fish had a single peak in October,
suggesting that DHP plays some role in the late stages of spermatogenesis.
(Department of Biology, Faculty of Education, Gifu
University, Gifu, Gifu 501-1193, Japan, Tel: 81-58-293-2255.Fax: 81-58-293-2259.
Email of Y. Koya: koya@cc.gifu-u.ac.jp)